1. Field of the Invention
The current invention relates to a method for the manufacture of fillings, and, more particularly, to a method for the manufacture of fillings for use in the mechanical processing of aqueous paper fiber stock.
2. Description of the Related Art
Fillings serve to disperse contaminants in the fiber stock, or deflaking in the refining of paper fibers, in other words they aid in the slushing of paper fiber agglomerates. They are then utilized in refiners, deflakers or dispergers. Machines are equipped with at least one rotor and at least one stator, having either discoid or conical surfaces on which the fillings are mounted, so that spaces can form between them. Many fillings have bars and channels on their working surfaces. This is the reason that they are frequently referred to as “knife type fillings”. Other fillings, for example, when used as inserts in dispergers are in the form of toothed rings. Disperger fillings are illustrated and described in DE 195 23 704 A1. It is known that, in addition to the shape of the bars, channels and teeth, the material from which they are manufactured also affects the processing of the fiber stock.
During the mechanical processing, that utilizes this type of filling, the paper fibers are present in the form of slush, with a solids content of approximately 2-8%, or as a viscous substance having a higher solids content. As a rule, dispergers operate at a solids content of between 15% and 25%.
The fillings are subject to wear and tear and must therefore be replaced at certain intervals. However, wear and tear may prematurely result in changes of the process operation. Shape, specifically an edge shape, and assembly surfaces have an overwhelming influence on the process. These changes present the disadvantage that, from a certain point in time forward, optimum results can no longer be achieved on the same machine.
It is therefore understandable that considerable expenditure is dedicated to the development of fillings, particularly to the design of their shape and to the selection of the material. It has been demonstrated that materials that are particularly suitable for the processing elements possess characteristics that may be very problematic if utilized for the base body of the assembly. This is particularly true of materials that are very hard and brittle, which do not possess the toughness that is necessary for the base body. In addition, such materials are relatively expensive and costly to produce, and in comparison with conventional metallic materials, can only be machined at great expense.
The base body of a processing tool represents the connection between the processing elements and the remaining components, such as those of a refiner. High stability requirements are imposed upon the base body, due to the high forces that occur in a refiner. It must also be feasible to mount the base body securely to the refiner, utilizing, for example, high torque rated screws. The base body is made of an especially strong and ductile material because of this requirement.
A method for the fabrication of fillings is already known from DE 196 03 548 A1, whereby they are assembled from components that are manufactured separately. According to this publication a high temperature soldering process conducted under a vacuum is utilized. Even though these methods are basically suitable, they are expensive in their execution and do not always result in sufficient stability.
A method for the production of refiner fillings is described in WO 99/37402 A 1, whereby it is also possible to select a different material for the blades as opposed to the base plate. However, this method is very expensive and complicated due to the multitude of individual components that have to be precisely assembled.
What is needed in the art is a method for the manufacture of the fillings so that their fabrication is substantially simplified and such that suitably hard materials, for highly stressed processing elements, can be used.